1. Field of the Invention
The present invention relates to an image processing apparatus, which applies color correction processing to original image data read by a photoelectric conversion device in an image scanner, facsimile machine, digital copier, and the like, and outputs it to a display device such as CRT, a printer device, or other output devices.
2. Prior Art
Generally, an image processing apparatus applies color correction processing to image data read by a photoelectric conversion device for each of colors, for example the three primary colors, i.e. RGB (red, green, and blue), and outputs the image data after correction to a display device such as a CRT or an output device such as a printer. A computer performs this correction with correction values according to characteristics of the output device so that a most faithful image to the original is obtained.
Meanwhile, for outputting the image data, it needs to be output in the order of the color constituents according to output information from the application software of the computer, and the like. That is, for image information that is read in the order of RGB, the output order of the RGB must be consistent with the reading format of the application software, for example TIFF, BMP, JPEG, and the like.
A conventional image reading apparatus is shown in FIG. 11. In the past, in this kind of image reading apparatus, a light source 104 irradiates a document 100, and the reflected light is separated into the three primary colors (constituents) of R, G, and B by passing through respective filters of R (red), G (green), and B (blue). They are incident to a photoelectric conversion element CCD 101, for example such as a CCD. The light (analog data) of each color constituent incident to the CCD 101 is input respectively into an A/D converter (analog to digital converter) 102 and digitized.
Data of digitized R, G, and B is corrected respectively in a shading correction component 302, a gamma correction component 303, and a line space correction component 304, and is temporarily stored in a regisLer 305, then it is input into a matrix operation circuit of a color correction component 306. In the shading correction component 302, shading correction processing, which corrects non-uniformity of the light intensity of the light source and irregularity of the sensitivity of the CCD image elements, is applied. In the gamma correction component 303, gamma correction processing, which corrects resolution of the respective R, G, and B data such that the output data resolution matches the resolution of the input data, is applied. In the line space correction component 304, line space correction processing, which adjusts shifting of the CCD read positions for R, G, and B, is applied.
Also, in the matrix operation circuit 306 of the color correction component, color correction processing such as a matrix operation shown below is performed using correction values for each color.
      Color    ⁢                  ⁢    Correction    ⁢                  ⁢    Matrix    ⁢                  ⁢          A      ⁢                          ⁢                          (                                                  R              ′                                                                          G              ′                                                                          B              ′                                          )        =            [                          ⁢                                                  K              11                                                          K              12                                                          K              13                                                                          K              21                                                          K              22                                                          K              23                                                                          K              31                                                          K              32                                                          K              33                                          ⁢                          ]        ⁡          [                                    R                                                G                                                B                              ]      
An original image and an output image have different characteristics in color, density, and the like, because of errors in filters that separate the colors into the three primary colors, spectral sensitivity characteristics of the CCD, and image generation characteristics of each output device (for example, printer, CRT, and the like). Thus, the image data from the CCD must be corrected by correction values. Generally, correction values R′, G′, and B′ are obtained by a matrix operation, which operates on input image data using a color correction matrix A. A method of this matrix operation is disclosed in Japanese Patent Publication (KOKAI) No. H5-122455.
Specifically, as shown in FIG. 11, the color correction matrix A specified according to the output device from color correction matrices stored in lookup tables 403 is temporarily stored in register 502. This color correction matrix A and the image data of R, G, and B are input into the matrix operation circuit 306, and color correction processing is performed electronically by matrix operations. Also, the image data corrected in this manner is transferred to a computer (PC 8) via an image data bus 9 and an I/F IC, and is output to an output device via an image handling application software, or is directly output to an output component like a facsimile or a digital copy machine, or the like.
At this time, the order of processing of each color constituent in the output device depends on specifications of an image processing software in the PC, or a printer engine of a facsimile or a digital copy machine. Thus, an order of each color constituent read by CCD needs to match to an order for image processing.
Conventionally, final data after color correction is converted to an order of color constituents according to an output device by a switching circuit (an output order changing component 600) provided in an output interface component. The output order changing component 600 comprises an output order changing circuit that changes (switches) an output order based on each output device, and this output order changing component 600 requires a switching controller device.
Accordingly, the apparatus and methods of the prior art require special electrical devices for changing the output order such as a switching circuit, and its controller, as well as a memory for switching, and the like. The apparatus tends to be complex and large, and furthermore it takes longer processing time.